Human-machine interfaces that are used to translate human movements to machine movements are used in myriad industries. For example, some aircraft flight control systems include a human-machine interface in the form of one or more control sticks. The flight control system, in response to input forces supplied to the control stick from the pilot, controls the movements of various aircraft flight control surfaces. No matter the particular end-use system, the human-machine interface preferably includes some type of haptic feedback mechanism back through the interface to the interface operator. In some implementations, the haptic feedback mechanisms are active mechanisms that include one or more electrically controlled motors that supply force feedback to the human-machine interface, typically via multiple gear stages that exhibit relatively high gear ratios.
Although useful and robust, feedback mechanisms that include multiple gear stages do exhibit certain drawbacks. For example, these gear stages, which are typically implemented using multi-stage planetary gears or harmonic drives, increase overall feedback mechanism inertia and friction, which can adversely affect overall system efficiency.
Hence, there is a need for a human-machine haptic feedback mechanism that includes one or more gear stages that exhibit less overall feedback mechanism inertia and friction, as compared to presently known systems. The present invention addresses at least this need.